Casing float valve



Feb. 22, 1944- c. N. PERcllFlELD, JR

CASING FLOAT VALVE Flved May 27, 1941 CharlesNPercmeliJn 1N VENTOR.

H15 ATTORNEY Patented Feb. 22, 1944 UNITED STATES PATENT OFFICE CASING FLOAT VALVE Charles N. Percield, Jr., Elect-ra, Tex.

Application May 27, 1941, Serial No. 395,492 `1 Claim. (Cl. 137-69) Thisv invention relates to an improvement in casing float valves of the character used in connection with the cementing of well casing, particularly in oil wells.

The cementing of well casing as practiced heretofore usually has involved the pumping of cement down through the casing to the lower end thereof where it is discharged into the well bore for securing the casing in place therein. A valve is provided usually at the lower end portion of the casing which acts as a check-valve to prevent the cement from being forced back. up the casing. Various forms of valves have been proposed and used for this purpose, but due to the fact that the opening in the valve plug through which the liquid cement must be pumped, is restricted by a valve stem, spring, or ball, such valve plugs have been found to be objectionable because of the lodging therein of foreign matter such as hemp rope, gloves, or large lumps of hardened cement, that get into the cement frequently and shut off the downward flow of the cement mixture past the valve plug. Such a stoppage creates a condition that is highly objectionable and expensive because it allows the cement to harden when it is stopped above the float, thereby choking the casing.

The object of this invention is to improve the construction of the lioat valve used in the casing by giving full and uninterrupted flow therethrough of the fluid cement past a valve member which is mounted for freedom of opening movement to a position substantially out of the path of flow, and yet will close the opening when desired against the upllow of cement through the l casing. This is accomplished by the provision of a hole through the plug which is of sufficient size to allow any foreign particles to pass therethrough, and by locating the valve member beneath the plug and so mounted that it is free to move to one side of the opening so as not to interfere with or clog the passage therethrough.

A preferred embodiment of the invention is illustrated in the accompanying drawing in which:

Fig. 1 is a longitudinal sectional view through a well bore showing the casing in place therein, with parts broken away and in section to illustrate an installation of the float valve;

Fig. 2 is a vertical sectional view through the float valve detached;

Fig. 3 is a bottom plan view thereof;

Fig. 4 is an enlarged vertical sectional view partly in elevation showing the float valve installed in the casing collar; and

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Fig. 5 is a similar view showing the float valve installed in the casing shoe.

Fig. 1 shows a conventional well bore I, having the usual casing 2 extending downwardly therein and supported at the desired point by means of clamps 3. The ycasing 2 is constructed of joints secured together by collars 4, screw-threaded thereon, and it is the usual practice to have a casing shoe 5 at the lower end thereof.

The collar 4 is telescoped over the adjacent ends of the casing joints as shown more in detail in Fig. 4, and has sufficient space between the ends of the joints to receive a float valve structure therebetween, as designated generally by the numeral 6.

The oat valve structure comprises a plug 1, which is of larger outside diameter than the inside diameter of the pipe joints, as shown in Fig. 4, and ts into the space or groove formed between the ends of the pipe joints. A packing ring 8 is interposed between the periphery of the plug 1 and the interior of the collar 4, being preferably of rubber or other packing material capable of embedding therein the threads formed on the interior of the collar 4 to provide a tight joint therebetween.

The plug 1 has an opening 9, shown as in the center thereof, which opening 9 is provided for the flow of cement therethrough and is adapted to be closed by a valve member I0 at the lower -side of the plug 1. The valve member I0 is pivotally supported on a pivot pin I I carried by ears I2, extending downwardly from the underside of the plug 1, and located in laterally spaced relation from the opening 9 in the plug. The valve member ID has a lip I3 thereon against which a coiled spring I4 bears, being interposed between said lip I3 and the plug 1. The plug 1 and the valve member I0 are constructed preferably of frangible, drillable material, such as cast iron, capable of being drilled out when desired. This valve member is mounted on the ears I2 so as to seat atly against the lower face of the plug 1 to provide a tight t therewith.

Many operators. prefer to mount -the casing oat valve about one joint of casing above the bottom which will insure proper cementing of the well to a substantial height. However, under some conditions, it is satisfactory to use the cas.- ing float valve within the shoe 5 forming a section at the lower end of the casing, as shown in Fig. 5. The valve structure 6 is installed in the casing shoe 5 substantially in the same manner as described above in connection with the collar t. The casing shoe 5 has a shoulder I5 immediately below its threaded coupling portion which prevents the valve structure 6 from being pushed downward while cement is being pumped into the well. The upward displacement of the valve structure G is prevented by its seating engagement against the lower end of the casing joint.

This valve structure is used in the usual manner, as described above. Liquid cement is pumped into the upper end of the casing and flows downward therethrough past the float valve structure 6, discharging from the lower end of the casing between the same and the wall of the well bore I, lling said space to cement the casing securely in the well bore. After the cement has been pumped into the well casing in sufficient quantity to cement the well, it is the usual practice to insert in the casing a cylindrical wooden plug of slightly smaller diameter than the casing, which is forced downward therein by pumping mud onto the top of the plug until the plug reaches the casing float valve 6. This will cause the cement within. the casing 2 to be forced downward through opening 9 below the Valve 6. When the wooden plug reaches the valve 6 the opening,r S will be closed and this will stall the pumps. Then by releasing the pressure slightly, the valve member ill will close and hold the cement beneath the float valve against upward flowing by Aback pressure through the casing until the cement sets.

As shown in dotted lines in Fig. 2, the valve member l@ is Capable of movement on its pivot pin il to a position substantially at one side of the opening S, so that it does not interfere with the downward flow oi cement therethrough, and

there is no substantial obstruction in the central opening which would obstruct the now of cement. Although the opening 9 is shown as substantially at the center of the plug l, it may be positioned at one side if desired, in order to provide a larger opening. This structure does not require the use of any special collar or shoe, being mounted and secured in place directly in the usual collar or shoe and coacting with the adjacent end of the casing joint to form an effective seal around the plug.

I claim:

In a casing float valve, the combination with upright pipe sections having inner end portions thereof spaced `apart and having a coupling sleeve connecting said pipe sections together, said spaced end portions being disposed inwardly of the sleeve and forming a groove therebetween and coacting with the sleeve to form a valve casing, of a fiat disc piug of uniform thickness and of less external diameter than the diameter of said groove to it loosely therein between the pipe sections, a packing ring surrounding said plug between the periphery of the plug and the coupling sleeve and holding the plug in place in the Sleeve, said plug having opening therein for the passage of cement therethrough, a disc valve member, means ivotely supporting the valve member on the under side oi the plug for closing said opening, said pivotal means being spaced inwardly from the periphery of the plug to allow said peripheral portion to be seated in the groove, and resilient means interposed between the plug and valve tending to Close the valve.

CHARLES N. PERCIFIELD, Je 

